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Pan Afr Med J. 2019 May 21;33:42. doi: 10.11604/pamj.2019.33.42.16666. eCollection 2019.
Outbreak of influenza A in a boarding school in South Africa, 2016.
Kleynhans J1,2, Treurnicht FK1, Cohen C1,3, Vedan T2, Seleka M1, Maki L4, von Gottberg A1,5, McCarthy K3,4, Ramkrishna W6, McMorrow M7,8, Walaza S1,3.
Author information
Abstract
Introduction:
We investigated an outbreak of influenza-like illness (ILI) at a boarding school in Eastern Cape Province, South Africa. We aimed to confirm the etiological agent, estimate attack rates and identify risk factors for illness.
Methods:
We conducted a retrospective cohort study including senior school boarders (n=308). Students with ILI (cough and fever) were identified through school medical records. We also conducted a questionnaire-based cross-sectional study among senior students including boarders (n=107) and day students (n=45). We collected respiratory specimens for respiratory pathogen testing by real-time polymerase chain reaction from a subset of symptomatic students. We calculated attack rates of medically attended ILI (medILI) and identified factors associated with medILI using logistic regression. We calculated seasonal influenza vaccine effectiveness (VE) against medILI.
Results:
Influenza A (H3N2) virus was detected in 61% (23/38) of specimens. Attack rate for medILI was 13% among boarders (39/308) in the cohort study and 20% in both day students (9/45) and boarders (21/107) in the cross-sectional study. Playing squash was associated with medILI (aOR 5.35, 95% confidence interval [95% CI]: 1.68-17.07). Of the boarders, 19% (57/308) were vaccinated before the outbreak. The adjusted VE against medILI was 18% (aOR 0.82, 95% CI 0.38-1.78). The outbreak led to cancellation of several events and the need for academic remedial sessions.
Conclusion:
We confirmed an influenza A (H3N2) virus outbreak with a high attack rate. The outbreak affected academic and sports activities. Participation in sports and social gatherings while experiencing ILI should be discouraged to reduce viral transmission and impact on school activities.
KEYWORDS:
Boarding school; cohort study; cross-sectional study; influenza; outbreak
PMID: 31384357 PMCID: PMC6658148 DOI: 10.11604/pamj.2019.33.42.16666
Free PMC Article
Outbreak of influenza A in a boarding school in South Africa, 2016.
Kleynhans J1,2, Treurnicht FK1, Cohen C1,3, Vedan T2, Seleka M1, Maki L4, von Gottberg A1,5, McCarthy K3,4, Ramkrishna W6, McMorrow M7,8, Walaza S1,3.
Author information
Abstract
Introduction:
We investigated an outbreak of influenza-like illness (ILI) at a boarding school in Eastern Cape Province, South Africa. We aimed to confirm the etiological agent, estimate attack rates and identify risk factors for illness.
Methods:
We conducted a retrospective cohort study including senior school boarders (n=308). Students with ILI (cough and fever) were identified through school medical records. We also conducted a questionnaire-based cross-sectional study among senior students including boarders (n=107) and day students (n=45). We collected respiratory specimens for respiratory pathogen testing by real-time polymerase chain reaction from a subset of symptomatic students. We calculated attack rates of medically attended ILI (medILI) and identified factors associated with medILI using logistic regression. We calculated seasonal influenza vaccine effectiveness (VE) against medILI.
Results:
Influenza A (H3N2) virus was detected in 61% (23/38) of specimens. Attack rate for medILI was 13% among boarders (39/308) in the cohort study and 20% in both day students (9/45) and boarders (21/107) in the cross-sectional study. Playing squash was associated with medILI (aOR 5.35, 95% confidence interval [95% CI]: 1.68-17.07). Of the boarders, 19% (57/308) were vaccinated before the outbreak. The adjusted VE against medILI was 18% (aOR 0.82, 95% CI 0.38-1.78). The outbreak led to cancellation of several events and the need for academic remedial sessions.
Conclusion:
We confirmed an influenza A (H3N2) virus outbreak with a high attack rate. The outbreak affected academic and sports activities. Participation in sports and social gatherings while experiencing ILI should be discouraged to reduce viral transmission and impact on school activities.
KEYWORDS:
Boarding school; cohort study; cross-sectional study; influenza; outbreak
PMID: 31384357 PMCID: PMC6658148 DOI: 10.11604/pamj.2019.33.42.16666
Free PMC Article